Abstract: A machine element has a shaft and at least a fitting member such as a cam or gear mounted on the shaft by pressure-fit. The fitting member has a bore for receiving the shaft. The shaft is formed with protrusions at least an area of the shaft on which the fitting member is fitted. The protrusions preferably extend continuously or discretely, peripherally or helically on the outer surface of the shaft and have a diameter larger than than the remaining areas of the shaft. The bore of the fitting member is formed with at east an inner chordal surface having a perpendicular from the center of the bore smaller than the radius of the protrusions. The fitting member is configured to be forced onto the protrusions of the shaft with at least one inner chordal surface forming a corresponding outer surface on the protrusions in a shaving and/or deforming operation.

Abstract: A compression ring as a piston ring adapted to by received in an annular groove formed in a piston disposed in a cylinder assembly of an internal combustion engine includes an annular ring base member having a cutout portion, the ring base member having an outer sliding surface, upper and lower surfaces continuous to the sliding surface through corner portions and an inner peripheral surface to be fitted to the piston groove, the sliding surface contacting an inner wall of the cylinder when the piston reciprocates therein. A nitriding layer is formed on all the surfaces of the ring base member by a nitriding treatment. A white portion of the nitriding layer formed only on the sliding surface of the ring base member is substantially completely removed and white portions of the nitriding layer formed on the first and second surfaces and corner portions between the sliding surface and the upper and lower surfaces are removed so as to reduce thicknesses thereof to not more than 5 .mu.m.

Abstract: A synchronizer ring having a stabilized friction characteristic relative to a taper cone and having sufficient mechanical strength and anti-abrasion characteristic. The synchronizer ring is made from a ferrous sintered alloy containing 0.2 to 1.0% by weight of carbon, 8.0 to 15.0% by weight of copper, 0.1 to 7.0% by weight of at least one component selected from a group consisting of chromium, manganese, molybdenum, and phosphorus, and balance iron and inevitable impurities. A free copper is precipitated in a matrix of the sintered alloy. Porosity of the sintered alloy is from 3 to 8 vol %.

Abstract: A synchronizer ring for performing synchronous sliding operation with and separating operation from a rotating object member, comprises a ring body having a sliding surface slidable in contact with the object member and a copper alloy flame-coated film formed on the sliding surface. The copper alloy flame-coated film has a Zn equivalent of 40 to 65, a surface porosity of 5 to 30 volume % and a thickness of 70 to 200 .mu.m. The copper alloy flame-coated film also may have a surface roughness (Rz) of 20 to 60 .mu.m, and a ceramic content of 5 to 30 weight %.

Abstract: A Cardan-type universal joint has a pair of joint bodies (11) each having a cylindrical hub (12) for securing thereto a rotary shaft (10), and a cross-shaped member (15) for connecting the pair of joint bodies together. Each of the hubs has at least one first slit, or escape slit, (20) formed therein radially inwardly from the circumference thereof having a sector shape with a sectoral angle of not less than 180 degrees and being disposed on a plane intersecting the axis of the shaft at an angle, thereby enabling the joint body to elastically deform in a spring-like manner.

Abstract: The object of the present invention is to provide a piston ring which is free from occurrence of cracks on the nitrided layer and having enhanced abrasion resistance and fatigue strength, and to provide a process for manufacturing the piston ring. In the invention, a surface of the steel body is subjected to a two-stage nitriding treatment consisting of low-temperature nitriding and high-temperature nitriding. A white layer on the slidable surface along the inner periphery surface of a cylinder is removed, and a white layer on each of the upper and lower surfaces and the corner portions each being adjacent to the slidable surface is removed to have a thickness of not more than 5 .mu.m.

Abstract: A mechanical element has a shaft pressure-fitted into at least one composite engaging member. The shaft has at least one engaging region disposed thereon, and at least one swollen portion formed radially outwardly around the engaging portion. The composite engaging member comprises an engaging body made of sintered alloy and having a recess therein, and a ring-shaped steel inner piece having a hardness not greater than the swollen portion. The inner piece is secured to the inside circumference of the recess of the engaging body by a securing method. The inner piece has a shaft hole formed therein, the shaft hole having a plurality of a larger inside diameter portions and a plurality of a smaller inside diameter portions arranged circumferentially, with the smaller inside diameter arranged to be smaller than the outside diameter of the swollen portion of the shaft.

Abstract: A secondary hardening type high temperature wear-resistant sintered alloy body comprising 0.4 to 15 wt. % of at least one species of metal carbide forming element which is selected from the group consisting of W, Mo, V, Ti, Nb, Ta and B; 5 to 35 wt. % of at least one species of austenite forming element which is selected from the group consisting of Ni, Co, Cu, and Cr; 0.2 to 1.2 wt. % of C; and 0.04 to 0.2 wt % of the remainder consisting essentially of Fe wherein the alloy body contains an austenite phase which is capable of martensitic transformation.

Abstract: A synchronizer ring for performing synchronous sliding operation with and separating operation from a rotating object member, comprises a ring body having a sliding surface in slidable contact with the object member and a molybdenum or molybdenum alloy flame-coated film formed on the sliding surface, the film having a ceramic present in an amount of 5 to 30 weight %. The flame-coated film may have a surface roughness (Rz) of 20 to 60 .mu.m. The flame-coated film may further have a surface porosity of 5 to 30%, preferably 7 to 25% and a film thickness of 70 to 200 .mu.m, preferably 90 to 120 .mu.m.

Abstract: In a process of casting a rocker arm as one piece from high chrome cast iron, a Ca-Si base addition agent is added to the molten metal in an amount of 0.3 to 0.6% by weight. The agent is effective as a globulizer to round high-hardness carbide precipitates directing toward the casting surface.

Abstract: A three-piece type oil ring assembly adapted to be fitted in an oil ring groove of a piston disposed within a cylinder comprises a spacer expander in the form of a gapped annulus made of section steel having substantially H-shaped radial cross section, and a pair of upper and lower side rails, each in the form of a gapped flat annulus. The spacer expander includes an axially protruding outer portion disposed on the outer circumference thereof and facing the inner surface of the cylinder, an axially protruding inner portion disposed on the inner circumference thereof and facing the innermost wall of the oil ring groove, and an axially flat connecting portion extending between the outer and inner protruding portions. The outer protruding portion has side rail supporting surfaces formed on the upper and lower ends thereof so as to be inclined toward the axially symmetrical centerline thereof along the radial direction at an acute angle with the radial direction.

Abstract: A composite plating bath prepared by adding an agent of boron compounds, such as trimethylamine-borane, dimethylamine-borane and sodium borohydride, by an amount of 0.1 to 10 grams/liter, preferably 1 to 8 grams/liter to a usual nickel electroplating bath having an aqueous acidic solution of at least one nickel salt and micron size particles of at least one water-insoluble material.

Abstract: A piston ring for use in an internal combustion engine. The piston ring includes a base body, a nitriding layer formed at an outer peripheral surface portion of the base body, and a composite Ni-B diffusion plating layer formed over the nitriding layer. The composite Ni-B diffusion plating layer has a thickness ranging from 0.5 to 20 micron meters. Since the nitriding layer is provided on at least the sliding surface of the piston ring, high durability of the piston ring can be attained because of the high wear resistivity of the nitriding layer. Further, since a Ni-Bi composite dispersion plating layer is formed over the nitriding layer, abnormal wearing due to scuffing is avoidable at an initial working phase because of the high scuffing resistance of the composite plating layer.

Abstract: A high strength high chromium cast iron contains fine particle precipitated hard carbide. The precipitated hard carbide has an average particle size of 20 .mu.m or less and hardness of Hv 500 or more in martensite base matrix, and has area ratio in a range of 30% or more and 45% or less. The precipitated hard carbide has spheroidal ratio (surface area of sphere circumscribing the precipitated hard carbide versus actual surface area of precipitated hard carbide) of 40% or more.

Abstract: An inline type check valve having a tubular body, a mushroom or umbrella-shaped piston axially, movably mounted in the tubular body, a coil spring disposed behind the piston in the body, and a hollow disk axially removably fixed to the body. Both the body and the disk made from a synthetic resin reinforced with fibers and resiliently hooked in each other. The piston has its periphery provided with a plurality of grooves to increase the cross-sectional area for fluid flow through the valve.

Abstract: A method for producing a camshaft having a tubular steel shaft and a sintered cam piece joined to the shaft. The sintered cam piece has iron tetroxide film at its surface. The camshaft is produced by assembling a powder compact to the steel shaft to provide a camshaft assembly, sintering the assembly to provide an integral assembly, correcting bending to the assembly, annealing the assembly, grinding the cam piece and effecting vaporization treatment to the assembly at a temperature lower than the annealing temperature.

Abstract: A universal joint having two joint bodies coupled together by a coupling member. Each of the joint bodies has a cylindrical hub portion and a pair of yoke portions provided integral with the hub portion by sintering, casting, or injection molding (die casting). The yokes are formed with bearing holes with which sleeve members are force-fittable. The coupling member has a rectangular segment formed with holes and separate pins force-fittable with the holes of the segment. Each of the pins is slidably inserted into each of the sleeve members fitted with the bearing holes, and extends into each of the holes of the rectangular segment.

Abstract: A two-piece type oil ring assembly consisting of a single spacer expander in the form of a split annulus and a side rail in the form of a flat split annulus. The spacer expander has a flat lower surface for making plane contact with the lower side of an oil ring groove when the assembly is mounted in the oil groove of a piston. The spacer expander has a radially, substantially L-shaped section composed of a trough portion, an outer crest portion integrally connected to the trough portion from outside, and an inner crest portion integrally connected to the trough portion from inside, the inner crest portion being taller than the outer crest portion. The spacer expander has a multiplicity of radial slots extending alternatively from the inner periphery of the inner crest portion to the inner periphery of the outer crest portion and from the outer periphery of the outer crest portion to the outer periphery of the inner crest portion. A plurality of oil grooves pass radially through the spacer expander.

Abstract: A camshaft comprising a steel shaft and a plurality of cam pieces fitted on the shaft. The cam piece is made from a sintering alloy material and bonded to the shaft by sintering. The shaft has pin-receiving holes perpendicular to the axis of the shift. The cam piece is formed on its side surface with a pin-receiving groove. A positioning pin has a lower portion tightly fitted in the hole of the shaft and an upper portion fitted in the groove to position the cam piece with respect to the shaft during sintering.

Abstract: A vane for a rotary fluid pump and a method for producing the vane are disclosed. The vane has a base vane body and an overlaid welding layer which functions as a sliding layer. The sliding layer is formed by using alloy powders and applying plasma arc to the end face of the base vane body. The alloy powders have high wear resistivity high resistance to thermal seizure and high corrosion resistance. During application of the plasma arc, the alloy powders are supplied, so that first and second layers are presented in the sliding layer. The first layer which is an inner layer is formed of a mixture of a material of the base vane body and the material of the alloy powders, and the second layer which is an outer layer is formed of the alloy powder material only.